Every parent will tell you that reliable and loving nannies are worth their weight in gold. And while it might be tempting to quickly hire someone who seems trustworthy for fear of the risk of losing them to other parents, for peace of mind in the longer run, it's important to investigate their health, background and attitude towards kids beforehand.
Call the previous employer
If the person you are interviewing seems reluctant to provide the details of her previous employer, or tells you that they got transferred out of the country, then your antenna should go up right away. I have, till date, no matter how nutty my life without a nanny was, never kept one without speaking to the previous employer. It is just a box that I have to check. Not that after that you can close your eyes and hire the person, but it helps to talk to someone with whom she has worked before.
Ask for identification/s
We all know this, but I am still surprised by the number of people who do not have their nanny's identification documents. This is an extremely vital step while hiring household help. Also, you need to keep a copy of that ID and get it verified by the concerned authorities. I maintain a file of all the people who have worked for me in the past as well. It's also a good idea to ask for more than one ID, just as a safety measure.
Get a medical test done
I have known friends who have hired help and later discovered contagious medical ailments (usually tuberculosis) that the nanny had. A medical is an absolute must before you hire help that is going to be in close proximity with your child. It can be tricky to ask someone, especially if she fits the bill and looks fit, to get some tests done. However, this is for your child's safety. I send all my helps for regular checkups as well.
If she is coming from an agency, check its credentials
Household work in India is not a regulated sector. This is why many of the so-called employment agencies that claim to provide perfect helpers for homes aren't proper companies. They are, mostly, being run by one person who changes his or her contact number so often that when you call next, you may well hear a 'number disconnected' message. You will not be able to chase anyone if things go wrong. This is why you must ask for the agency's bank details and insist on making a cheque payment for their services.
Ask her if she has the patience to deal with children
Dealing with children can test your patience levels. If parents can sometimes lose their cool, then nannies too could feel the same at times. You need to know how comfortable your help is with children before you hire them. You don't want someone who is prone to anger to become your child's caretaker. This, you have to test by asking her a few simple questions about children. Give her a situation, ask her, for instance what she would do if your child threw a tantrum. While she may give you all the right answers, you will still be able to judge from her reaction about how she will handle a child.
Also, for the first month or so, do not leave your child alone with the help. You must also click a picture of hers and have her know that you've kept it for your records. It can be scary to hire a total stranger and leave your home and child to her. Take all the precautions and always have your guard up for any odd behaviour.